Modal Verbs for Ability

There are three modal verbs used to show ability:

• Can
  
• Could
  
• Be Able To

Examples:

Present

• I can play the guitar.
  
• She can speak German.
  

* Can is always followed by a base verb.Past

• I could sing very well when I was young.
  
• She could read when she was 2 years old.
  

Future

• I will be able to drive a car in 2 years.
  
• He will be able to buy a house next year.
  

"Able to" is used with many other verb tenses.  Take a look at
these examples:

• I have been able to visit many countries in my life.
  
• I used to be able to dance the Tango.
  
• I will have been able to finish by tomorrow.
  

Negatives
Negatives are formed by using "not".

• I can not play piano.
  
• She can't play piano.
  

• She could not finish her homework last night.
  
• They couldn't finish their homework last night.
  

• I will not be able to go to the party tonight.
  
• Susan won't be able to go to the party tonight.
  

Questions 
Questions are formed by changing the order of the words.

• Can you drive a car?
  
• Could he swim?
  
• Will Doug be able to bring his boots?
  

Notice that "will be able to" is separated when used in a
question:

• Will he be able to finish on time?